In automatic testing of integrated circuits (IC) and other electronic devices, special device handlers have been used which brings the device to the proper temperature and places the device to be tested in position. The electronic testing itself is provided by a large and expensive automatic testing system which includes a test head which has been required to connect to and dock with the device handler. In such testing systems, the test head has usually been very heavy on the order of 40 to 400 kilograms. The reason for this weight is that the test head uses precision high frequency control and data signals so that the electronic circuits may be located as close as possible to the device under test. Accordingly, the test head has been densely packaged with electronic circuits in order to achieve accurate high speed testing of the sophisticated devices.
Test head positioner systems may be used to position the test head with respect to the device handler. When the test head is accurately in position with respect to the device handler, the test head and the device handler are said to be aligned. When the test head and device handler are aligned, the fragile test head and device handler electrical connectors can be brought together (i.e. docked), enabling the transfer of test signals between the test head and the device handler. Prior to docking, the fragile test head and device handler electrical connectors must be precisely aligned to avoid damaging the fragile electrical connectors.
As shown in U.S. Pat. Nos. 4,527,942 and 5,440,943, a positioner, able to move along a support structure, carries the test head to the desired location at which the test head is positioned to connect to and dock with the device handler. The test head is attached to the positioners so that the test head can achieve up to six degrees of freedom (X, Y, Z, .theta.X, .theta.Y, .theta.Z).
Test heads, and their respective positioners, are often used in an clean room environment. However, clean room environments are often extremely expensive to provide. Thus, the useable space within an ultraclean environment is only available at a premium.
A variety of test head manipulators are currently available for use in ultraclean room environments. Although some of these test head manipulators have a variety of desirable features, the amount of space which each of these test head manipulators requires for proper operation may be undesirable.
As device testing in general, and the use of test head and device handlers in particular, becomes developed to handle ever more increasingly complex tasks, test heads continue to become larger and larger. This increase relates both to the physical size and weight of the test head. However, as test heads get larger and larger, fully manual, fully balanced systems have become ever more difficult to design.